The product of the transforming gene of Rous sarcoma virus (pp60src) is responsible for the initiation and maintenance of neoplastic transformation. This transforming protein is found within various cytoplasmic compartments and is concentrated within adhesion plaques of RSV transformed cells. The research proposed in this application involves studies on the mechanism of transformation by pp60src with specific emphasis on analyses of the interaction of pp60src with cellular components, such as adhesion plaques, and the subsequent phenotypic alterations induced by these interactions. Potential antigenic and functional domains on pp60src will be analyzed by preparing antibodies to synthetic peptides from defined regions of pp60src. Functional activity of these domains will be assessed by the ability of the antibody to neutralize either the in vitro kinase activity or the expression of other transformation parameters after microinjection into living cells. Similar techniques will be used to identify regions of pp60src involved in adhesion plaque binding, the induction of the fusiform morphology, and the loss of cell surface fibronectin. Monoclonal antibodies will be prepared to pp60src substrates (vinculin and 36K protein) and microinjection used to evaluate potential functions connected with these proteins. Microinjection also will be utilized to study intracellular movements of rhodamine-labeled pp60src. Further studies on specific functions of individual adhesion plaque proteins and their possible involvement in RSV-induced transformation will employ production of monoclonal antibodies to these proteins. Results from these studies should contribute to our understanding of the neoplastic process.